One goal for the coming year is to study the sperm-egg interactions and the effect of reproductive tract secretions on this interaction. We will investigate the role of chemotaxis in the union of the gametes. We will also determine if the expression of recessive lethal genes cause death of the parthenote shortly after implantation. One pronucleus will be removed microsurgically from the fertilized LT zygote, and the resulting haploid zygote diploidized with cytochalasin B. Full-term development of the completely homozygous LT embryo would indicate that the expression of recessive lethal genes is not the cause of LT parthenote embryos. We will contiue to study the genetic basis of BALB/c Wt hermaphrodites and hope to establish the role of the rete in inducing premature meiosis in male tubules. We will use the hermaphrodites to study the role of the Hy antigen in male development. We will search for XYY males in BALB/c Wt and other strains of mice. The collection of data on pituitary and circulating hormones is essential to elucidating the reasons for reproductive failure. We will determine the pituitary content and circulating levels of gonadotropins and the major sex steroids with currently functioning radioimmunoassays. Mice of the following inbred strains and genotypes are scheduled for immediate examination: BALB/cWt hermaphrodites with both male and female littermate controls; SWR/J - females bearing ovarian granulosa cell-like tumors and non-tumorous female controls; an/an and an/plus female controls; and lit/lit and lit/plus male controls. BIBLIOGRAPHIC REFERENCES: Whitten, W. K. 1976. Responses to Mammalian Pheromones. Proc. V. Inter. Sym. on Olfaction and Taste, Academic Press, New York. Whitten, W. K., and W. G. Beamer. 1976. 2401 Sex Combinations. Proceedings of New England Endocrinology Conference (abstract).